86 J. J. STEVENSON — LOWER (?ARBONIFKROUS, APPALACHIAX BASIN 



in 1901, Stevenson collected carefully at a localit}^ in Fayette county of 

 Pennsylvania and submitted the specimens to Mr Weller, who found 

 that the fauna contains some Saint Louis as well as the Chester forms. 

 There is, however, practically no change in the fauna from the bottom 

 to the top of this localit3% the same forms, with two or three exceptions, 

 being found throughout. The Chester forms predominate, and of those 

 belonging to the Saint Louis some lived on into the Chester at typical 

 localities within the Mississippi basin. The same fauna occurs in Ran- 

 dolph county of east central West Virginia and in Washington count}- 

 of Virginia at the Tennessee border. In Tennessee and Alabama the 

 Maxville (Hartselle) is clearl}^ Chester. The Kentucky geologists of the 

 second survey make the Maxville the upper part of their Saint Louis, 

 but it overlies the Lithostrotion bed, the lower part of their Saint Louis. 

 No list is given of the fossils which lead to classification of the limestone 

 as Saint Louis. 



The Tuscumbia is practically non-fossiliferous at most localities in 

 Pennsylvania. In Tennessee and Alabama, as well as in Kentuck3% 

 Lithostrotion canadenslsis the characteristic fossil, and it is associated with 

 other forms belonging to the Saint Louis. 



Physical Changes during the Mississipfian 



the la ter de von i a n 



The several deposits have been traced throughout the basin in such 

 detail as available observations permit. It remains to ascertain, if pos- 

 sible, what geographical changes and stratigraphical disturbances took 

 place during the Mississippian, but it is necessary first to make reference 

 to conditions existing during the later Devonian. 



During the Chemung (Jenning) the area of sedimentation extended 

 from the Appalachian shore westward across Penns3dvania into north- 

 ern Ohio; across Virginia and West Virginia, evidenth^ to the Ohio 

 river; southward from the line of central Virginia the area contracts. 

 There appears to be no Chemung in Kentucky, none in Tennessee, ex- 

 cept on the eastern side of the basin, while in Georgia it is confined to 

 a narrow strip following the old shoreline. The Chemung basin was 

 very broad at the north, reaching far into New York and crossing into 

 northeastern Ohio, but it tapered southward, the contraction being on 

 the westerly side, until it disappeared in Georgia. The area of more 

 rapid subsidence, lying near the old shoreline, was narrow throughout, 

 reaching north, from New river of V^irginia, to only a few miles beyond 

 the Alleghany region. The vast thickness observed along the eastern 

 border decreases so quickly" in southern Pennsylvania that before the 



